The present invention is an improvement of the apparatus disclosed in U.S. Pat. No. 4,103,739.
Typically during oil production, a pump will be required at some stage to lift the oil from the well. The pumps are utilized to produce oil from low pressure formations. These pumps are normally inserted into the tubing string inside the production casing and are located near the producing zone. The casing string is typically perforated to allow the formation fluid to flow from the surrounding formation into the casing. The tubing string is open at the bottom to allow fluid to enter. The materials produced are typically a mixture of oil, water, and sand in varying ratios. The pump is utilized to incrementally lift the materials produced from the formation up the tubing string to where it is collected at the surface.
The housing of the pump leaves a space between the outer surface of the pump and the inner surface of the tubing string. This annular space collects sand from the sand bearing mixture after pulling the liquid through the pump housing for delivery through the pump tubing. During the time that the mixture stands between the pump and the tubing string, the difference in the specific gravity of the sand particles and the water/oil mixture causes significant settling of the sand particles. This sand collects and builds up around the lower portion of the pump housing and connected string and clogs the space above the pump supporting nipple or in shoulder which holds the pump. This sand build up normally does not interfere with the pump action or the lifting of the mixture produced from the formation.
Periodically all pumps utilized for lifting the oil/water mixture to the surface need to be serviced. To service these pumps, it is essential that the sucker rods and pump be lifted from the well and serviced at the surface. One problem that periodically occurs is that the sand build up around the housing of the pump and locks the pump in place thereby preventing removal of the pump and sucker rods.
U.S. Pat. No. 4,103,739 discloses an apparatus which extends to allow the sand collected around the pump housing to wash through slotted openings thereby clearing the annular space around the pump. While that apparatus has proved to be successful in freeing the pump most of the time, on occasion the pump still cannot be removed. The present invention is an apparatus to allow tool removal in those situations. The present invention is connected to the lower portion of a production pump. It is primarily a pair of telescoping members that conforms in size and shape to the typical production pump. The apparatus is prevented from telescoping by shear pins which normally maintain the apparatus in the non-extended or pumping position. While in this position, the drain slots are not exposed and the pump operates in a normal fashion. When removing the pump and connected sucker rods, the load on the shear pins for removal of the pump is an acceptable and known load assuming the pump is not sand locked. The shearing force required for the shear pins is in excess of that amount of pull. During typical pump removal, the shear pins are not sheared and the telescoping members remain in the closed condition without extending. This allows normal removal of the pump and sucker rods.
On the other hand, if the pump is sand locked, the present invention comes into play. The innermost sleeve member is initially threaded to the pump hold down which rests on the inwardly protruding shoulder of the tubing string. The outermost sleeve member is connected by a left-hand thread to a double male threaded coupling or adapter which is in turn threaded to the lower portion of the pump apparatus. Movement of the two sleeve members is prevented by one or more selectively sized shear pins. The innermost tubular member has a surrounding and protruding lip at the upper end which is sufficiently large to lock it against pulling through the outer tubular member. If the pump is sand locked, the normal pull is exceeded until the upward pull breaks the shear pins which join the telescoped tubular members. When the shear pins are broken, the outer tubular member slides upwardly to expose a set of drain slots which are adjacent to the sand locking the pump. The hydrostatic pressure of the fluid column above the sand washes the sand down through the slots and then through the center of the tool and out through the bottom. Typically, this washing action will free the sand locked pump. Occasionally, this washing action is insufficient, and the pump remains sand locked. At this time, the improvements of the present apparatus are required to free the sand locked pump.
In addition to the first set of shear pins discussed above, a second set of one or more pins extends through the outer sleeve member to pass through the drain slots while in the non-extended position. The length of the drain slots is sufficient such that the second set of pins do not restrict the telescoping movement of the present invention. The purpose of the second set of pins is to prevent rotational movement of the sleeves with respect to each other.
As was previously noted, the outermost sleeve member is attached to a double male threaded coupling or adapter through the use of left handed threads. In the situation where the pump is still sand locked after the first shear pins are sheared and the flushing action has taken place, the sucker rods and pump are rotated to the right unthreading the left handed thread connection between the present apparatus and the bottom of the pump. Once rotated sufficiently, the rods and pump can be separated from the present apparatus, pulled up the well and brought to the surface.